Communication and Capability URLs in COAST-based Decentralized Services

Abstract

Decentralized systems are systems-of-systems whose services are governed by two or more separate organizations under distinct spheres of authority. Coordinated evolution of the various elements of a decentralized system may be difficult, if not impossible, as individual organizations evolve their service offerings in response to organization-and service-specific pressures, including market demand, technology, competitive and cooperative interests, and funding. Consequently, decentralized services offer unique challenges for evolution and adaptation that reach well beyond any one single organizational boundary. However, client-driven service customization and tailoring is a powerful tool for meeting conflicting, independent client demands in an environment where disorderly and uneven service evolution predominates. Computational State Transfer (COAST) relies on capability security to minimize the risks of client-driven customization, for which fine-grain management of communication capability is critical. We introduce the Capability URL (CURL) as the unit of communication capability and show how two distinct mechanisms, communication capability and mobile code, can be combined to express and enforce constraints on the communications among decentralized computations.